Considerations for the Seismic Assessment of Buildings Using the Direct Displacement-Based Assessment Approach

The seismic assessment of a structure can be affected by many factors, with numerous sources of uncertainty connected with the definition of material characteristics, structural load-paths and the possible formation of different plastic mechanisms. Consequently, in comparison to the seismic design of new buildings, it is considerably more difficult to make a precise seismic risk assessment of existing buildings. Nonetheless, it is well recognized that even a good seismic design solution requires accurate and rational design methods, and in recent years the Direct displacement-based design approach has emerged as a reliable method that could well be implemented within seismic design codes in the future. In the light of this, and with reference to the new Italian national research project RELUIS, this paper presents the Direct displacement-based assessment methodology for the assessment of existing structures and discusses how uncertainties in the assessment could possibly be accounted for probabilistically. The approach is illustrated with reference to a 6-storey RC frame structure and by comparing the assessment results with those obtained from non-linear pushover analyses it is shown that the approach may offer good possibilities for the seismic assessment of structures. In addition, after briefly reviewing recent research on loss assessment methodologies, it is proposed that simplified probabilistic considerations could be made to permit loss assessments of individual structures.